But thousands of Americans have been persuaded otherwise, falling victim to a fast-moving scam that claims to be part of an Obama administration program to help pay utility bills in the midst of a scorching summer.

The scheme spread quickly across the nation in recent weeks with help from victims who unwittingly shared it on social media sites before realizing they had been conned out of personal information such as Social Security, credit card and checking account numbers.

"No one knows who is behind this," said Katherine Hutt, spokeswoman for the Council of Better Business Bureaus in Arlington, Va. "We're pretty concerned. It seems to have really taken off."

People from all corners of the country report being duped, from New Jersey to California, Wisconsin to Florida and all parts in between.

The scam benefits from being cleverly executed and comes at a time when air conditioners in much of the country are running around the clock to tame record-high temperatures.

Here's how it works: Victims typically receive an automated phone call informing them of the nonexistent utility program that will supposedly pay up to $1,000. There have also been reports of the hoax spreading by text message, flyers left at homes and even personal visits.

Victims are told that all they have to do is provide their personal information. In exchange, they are given a bank routing number and checking account number to provide their utility company when making a payment.

The swindle works because the payments with the fake bank account number are initially accepted. Only when the payments are processed hours or days later is the fake number caught and rejected.

But by then, victims have told friends about the offer, posted it online and, most important, turned over personal information that could allow con artists to dip into their bank accounts or steal their identity.

There's no way to accurately measure how many people have been affected, "but this one feels like it's pretty widespread," Hutt said.

Taneisha Morris' sister was drawn into the hoax after a friend received a text promising federal assistance with her bills. The sister sent the information to Morris, a Detroit woman who is unemployed after losing her job as a manager at a KFC restaurant.

Morris quickly took advantage, providing her Social Security number and asking for $187 toward her DirecTV bill and $800 toward what she owed DTE Energy, a Michigan utility.

"It was very disappointing to me," Morris said Thursday after learning she had been deceived. "They shouldn't do that to people. I just lost my job in February, so it's very hard for me to come up with extra money."

It wasn't clear whether law enforcement agencies were investigating. A message left with the Federal Bureau of Investigation in Washington was not immediately returned.

The first reports of the hoax surfaced in the spring and spiked in May and early July. Utilities and Better Business Bureau offices swiftly issued warnings.

"We see a lot of door-to-door scams," Hutt said. "It is somewhat unusual to see one that's so well tied-together. There could be copycats in there. We're not entirely sure. At this point it's probably more than one scammer."

Victims appear to be concentrated in New Jersey, where about 10,000 customers of Public Service Electric & Gas were conned. The first complaints arrived in May, but the bulk of them came over a six-day period in late May and early June, company spokeswoman Bonnie Sheppard said.

The scam quickly grew as victims shared the word on social media, "thinking it was a legitimate federally sponsored program," Sheppard said. "And of course, that can become confusing because there are legitimate federally sponsored programs."

There have been numerous other reports:

• Entergy Corp. said in May that about 2,000 of its customers had been affected, mainly in Louisiana but also in Texas.

• About 1,500 Duke Energy customers in the Carolinas and a few in its Midwestern states were duped, company spokeswoman Paige Layne said.

• Atmos Energy, one of the country's largest natural gas distributors, issued a warning in May to its 3.2 million customers in 12 states after about 300 customers in Mississippi reported being conned, company spokeswoman Jennifer Ryan said. Atmos sent out a second warning in July.

"It's gaining some ground," Ryan said of the ruse.

• Between 90 and 100 bogus payments came into Alliant Energy Corp., which serves about 1 million people in southern Wisconsin, most of Iowa and southern Minnesota, spokesman Scott Reigstad said.

The Better Business Bureau and others are warning people not to share personal information unless they have initiated the contact and are confident in other person.

"We try to make this as easy and quick to grasp for anyone," said Janet Hart with the BBB in the Carolinas. "Never give out your personal information to someone who calls you."